The iCalendar module for Python is available from www.mxm.dk/products/public/ical/downloads.
For more detailed information about working with dates and times in PostgreSQL, a FAQ written by Josh Berkus is at techdocs.postgresql.org/techdocs/faqdatesintervals.php.
The Psycopg database adapter for Python and PostgreSQL is at initd.org/projects/psycopg1.
You can download the latest build of the Mozilla calendar extension, or of the Sunbird standalone application, from www.mozilla.org/projects/calendar/download.html.
The RFC for iCalendar is available at www.ietf.org/rfc/rfc2445.txt.